Following the maximum of four treatment cycles, each subject will be followed for additional safety and efficacy assessments on Days 169 (± 7 days), 232 (± 7 days), 295 (± 7 days), 365 (± 7 days) (nominal weeks 24, 33, 42 and 52). Subjects randomized to placebo may receive open-label AA4500 treatment after completing this study as part of another protocol.